Aviation safety investigations & reports

Near collision between a Pacific CT4B, VH-YAB and a Beech 1900D, VH-NTL, 4 km NE Armidale, 20 June 2000

Summary

The pilot of an Instrument Flight Rules (IFR) CT4 Airtrainer
made an inbound report on the Armidale common traffic advisory
frequency (CTAF) when at 8 NM southwest of the aerodrome. Four
minutes later the pilot broadcast that he was overhead, with the
intention of conducting an NDB/DME approach to runway 05.

Subsequently, an IFR Beech 1900 taxied at Armidale for departure
from runway 05. Both aircraft had been given traffic information on
each other by Brisbane air traffic services. When the Beech 1900
crew broadcast that they were taxiing, the CT4 pilot advised that
he was about to turn inbound on the sector 1 entry for the runway
05 NDB/DME procedure and was maintaining 5,800 ft.

The Beech 1900 crew acknowledged the call. The CT4 pilot then
awaited the lining up or rolling call from the Beech 1900 crew so
that they could arrange mutual separation.

After completing the inbound turn the CT4 had approximately 2 NM
to run on the inbound leg of the sector 1 entry. At that stage the
pilot observed a Traffic Collision Alert Device (TCAD) indication
that an aircraft was 1,100 ft below, climbing directly toward his
aircraft and at a distance of 1.3 NM. The CT4 pilot therefore made
an immediate broadcast on the CTAF, transmitting his position as 2
NM northeast at 5,800 ft. The Beech 1900 crew responded stating
that they were in a right turn passing 5,800 ft. The pilot of the
CT4 then observed, through a break in the cloud, the Beech 1900 in
his 6 o'clock position at the same level and moving away.

The Beech 1900 crew reported that while maintaining runway
heading after takeoff, they levelled at 4,500 ft for a short time
to ensure separation. They later stated that they had interpreted
the CT4's position as being outbound on the Runway 05 NDB approach
and to the south-west of the NDB; therefore, it was not perceived
to be a confliction.

The CT4 pilot reported the conditions as generally IMC with a
few breaks in the cloud at his level but with no significant
vertical visibility. The Beech 1900 continued climbing in a right
turn in accordance with the published company procedures for IMC
departures at Armidale. The CT4 landed from the runway 05 NDB
approach without further incident.

Recorded radio transmissions confirmed that the Beech 1900 crew
gave a taxi broadcast for runway 05 that included the phrase
"shortly entering and backtracking". They did not subsequently
advise that they were about to commence take-off, as directed in
the Aeronautical Information Publication. The crew could not
explain that oversight.

Analysis

The crew of the Beech 1900 thought that the CT4 did not pose a
confliction. Nevertheless, it may have been prudent for them to
ensure mutual agreement on some form of vertical separation even if
their expectations of lateral separation had been correct. Their
lack of situational awareness and omission of a broadcast advising
they were commencing take-off, combined to create a situation with
potentially serious consequences.

The investigation was unable to determine whether the crew's
action in maintaining 4,500 ft was a result of the prompting from
the CT4 pilot in response to the TCAD warning or because they
suddenly realised their lack of situational awareness.

Flight crews are required to continually assess the aircraft,
its flight path and the people who interact with it in order to fly
safely. The safety value of on-board defensive systems such as TCAD
was demonstrated in the incident.

Safety Action

As a result of this occurrence, the Beech 1900 operator has
taken the following safety actions:

Introduced and incorporated procedures into the Operations
Manual that would assist operating flight crew to ensure separation
with mutual air traffic;

Reviewed all of their aerodrome procedures for potential
ambiguities; and

Published their investigation of this occurrence for the
information of all operating crew as a reminder of the necessity
for compliance with all mandatory broadcast transmissions at all
times.